This invention relates to methods for moving objects or foods within treatment chambers.
A large number of situations are known to exist in which eatable or non-eatable objects have to be placed in treatment chambers for their cooking, leavening, cooling, heating, dehydration, irradiation and/or technical treatment.
There are also situations in which certain products have to be treated with electromagnetic, sterilizing or anti-sprouting radiation.
In such situations, a given object has always substantially been transferred from usual environmental conditions into a treatment chamber by means of a transit vehicle, undergo the required heating or treatment, and finally emerge into the environment where it is withdrawn for use or for packaging.
These steps are currently achieved in various ways, of which the following are the most typical, and enable the object or product to be regulated by residing for the time required to reach the exit, it being loaded and discharged continuously. The most simple is the tunnel method by which the product is rested on a conveyor belt or the like which passes through a treatment chamber, receiving its load before entering, to discharge it after it has left the tunnel.
This method has the drawback of a considerable longitudinal space requirement associated with a considerable radiant surface which makes it difficult to maintain the required temperature. An improvement in this method is to use two overlying conveyor belts sliding in opposite directions to enable the objects conveyed by the upper entry belt to fall onto the lower belt which conveys it to the exit. This method is however applicable only to products which can be processed in loose form.
There is also the tower method by which the product is made to travel through a path in the form of a cylindrical helix of vertical axis until it leaves from the top.
This method has the drawback of not using the total volume of the treatment chamber in that the helical curvature of the articulated belt leaves a central air column free. When conveyed to the top the product has to be made to again descend to the operating floor level by chutes which generally endanger the shape of the product and prevent a hypothetical precise order or location of the various objects or products from being maintained.
If the objects or products have to be handled in a predetermined arrangement on specific trays, these trays must be stacked on trolleys provided for transporting them and maintaining them within the treatment chamber for the required time.
This latter method is a batch method and creates problems connected with the required operational continuity of the processing necessary downstream of the thermal cycle.
Methods for handling such products currently exist based on the use of flexible trays formed from thin metal sheet, but these have the drawback of having to always operate with outer longitudinal bars to provide them with the stiffness necessary for them to transport or support the products.